Pick boxes of rotary cutting heads or drums of mineral winning machines or tunnel driving machines are frequently fitted with screw-in water spray nozzles, particularly if coal mining is involved, for a variety of well established reasons. The propensity for damage to the nozzles has led to the adoption of so-called rear-entry spray nozzles, whereby the nozzle is screwed into, and out of its receiving bore, from the rear of the pick box.
Inevitably, in service conditions nozzle blockage and/or damage occurs, and whilst blockage of a few nozzles e.g. on a cutting head carrying 50-100 pick boxes and associated nozzles might be tolerated, modern mining machines monitor both water flow and pressure so that keeping the nozzles operational is critical to avoid automatic machine shut-down, and consequently nozzle removal, inspection, cleaning and/or replacement followed by replacement of a cleaned or new nozzle, in mine conditions is involved.
In addition, to achieve a desired spray pattern—usually a hollow or solid cone—the spray nozzle is a precision component and hence relatively expensive if replacement, and in particular multiple replacement, is required.
A basic object of the invention is the provision of an improved water spray assembly and a pick box incorporating such an assembly.